“The Fenian Ram” By Paul Gray
In 1999 I had the chance to visit the Patterson Museum in Patterson NJ. It was a dreary rainy day during the week and I was passing through on my way to attend a conference at Stevens Tech in Hoboken. At this time I had been into the engine hobby about 7 years. As I was touring the museum, I went to look at “The Fenian Ram” ; John Holland’s second submarine. The plaquard said it was powered by a Brayton cycle engine. Now my interest was peaked and I approached the curator, Bruce Balistrieri and told him about my hobby and my interest in such an unusual engine. He asked me if I would like to climb inside and see it for myself... I was in there for the better part of an hour.
The Fenian Ram was designed by John Holland and launched in 1881. The secretary of the Navy, upon first seeing his design proclaimed it as “a fantastic scheme of a civilian landsman”. Holland’s brother, Michael, had been introduced to the Fenian Movement who had organised a skirmishing fund. The purpose of the fund was to build a 3-man submarine to use against the British Navy. Work on Holland’s second boat was begun in May 1879 at the Delamater Iron Works in Manhattan, and it was launched into the Hudson River two years later. The Ram’s hull was 31 feet long and roughly six feet in diameter, with a shallow conning turret on top. Armed with a co-axial pneumatic “dynamite gun” in the bow, the 19-ton boat was intended to support a crew of three: a commander, an engineer, and a gunner. The Ram was capable of nine knots, depths of 50 feet, and stayed down for as long as an hour during tests, which took up to two years to complete. The Fenians, frustrated with Holland's delays and, faced with internal legal squabbles, stole their own boat and hid it in a shed in New Haven, Connecticut, where it remained for 35 years. Holland had nothing more to do with the Fenians, and the boat was eventually donated to the city of Patterson, where it is sits now.
The Brayton-cycle engine differs from the familar Otto cycle in that instead of compressing the fuel-air charge and then igniting it, the Brayton cycle injects a compressed fuel-air charge into a cylinder where it is ignited and continues to be injected and burned for roughly half of the power stroke. After the fuel-air injection ceases, the remaining hot gasses in the cylinder are allowed to expand until the bottom of the stroke is reached. Then an exhaust valve opens and the spent mixture is forced out of the cylinder. The Brayton-cycle is referred to in engineering lingo as a constant-pressure cycle. A modern jet engine is also called a Brayton cycle but instead of pushing a piston, the compressed fuel air mix is burned and allowed to turn a turbine.
Fig 1-The Fenian Ram on display. The engine and crew compartment occupies the center third of the sub.
The Brayton engine in the Ram is a unique design. It has two tandem cylinders driven from both sides on the outside of a crosshead between them. The crankshaft has 2 throws in the same position. The front power cylinder operates off of compressed air generated by the rear cylinder. A reciever stores the excess compressed air. Fuel is metered in the intake ports by small injection pumps. These pumps were crude by today’s standards employung a plunder and a slide valve to direct the fuel ti the cylinder. The valve mechanism, fuel pump and governer appears to be driven off of a toothed chain. On the top of the ends of the power cylinder are openings which I believe are for inserting either a preheated platinum sponge or a burning wick. In operation, the ignitors are inserted in these ports and the air turned on. The Brayton literally air started itself.
Figure 2- View of the sub interior showing the Brayton engine cylinders on the starboard side. The hatch is located just above the large bevel gear on the center right.
John Holland was clever in using a Brayton engine in his submarines as the excess compressed air was probably pumped into large tanks in the front and rear of the sub for blowing ballast and possibly operating the engine. I do not know whether the sub ran powered while under water using the stored compressed air. If it did, I am sure it would not have travelled far since the pumping cylinders were capable of pumping the air tanks to 80-100 psi. The trail of bubbles from the sub operating under power would have been a dead giveaway as to its position.
All the literature I have seen on the Brayton has shown the pumping cylinders to be about 50% of the power cylinder volume to maintain adequate air volume for running the engine. Lyle Cummins’ book, Internal Fire has an excellent chapter on this unique engine. Brayton’s first engines compressed a mix of gas and air in a receiver where it was then metered into the cylinder. A screen plate between the compressed gas supply and near the intake valve prevented the compressed gas mixture from exploding in the receiver. Still, explosions in the receiver did occur popping a safety valve much to the discomfort of the operator. Later Brayton engine designs utilized oil vaporization at the intake valve area by a wick arrangement. As the air rushed by on the admission period, atomized oil was carried through the screen or grating into the cylinder.
Figure 3- Front end of the Brayton showing the main parts of the power cylinder. The valves are actuated by a cam driven by a toothed chain on the far side.
The grating in the intake valve area was a key invention for keeping the combustion products within the cylinder. The Brayton always operated with the pressure in the power cylinder being less than the compressed air supply. Additional volume of gasses to produce useful work was generated by burning fuel in the cylinder.
Figure 4- View looking aft from the fron wall of the crew compartment. To get out of the sub, you have to crawl on top of the bevel gears which drive the propeller.
Most of the illustrations in Cummins’ book show a sideshaft driving the governer, valving and fuel pumps. Perhaps space constraints necessitated using a chain-like affair to drive them in the Fenian Ram. As you can see, space was limited inside the Ram. I had to crawl down on top of the large bevel gear which drove the propeller to get inside. No doubt being aboard this sub while it was under power could have been a scary experience with the spinning flywheel, gears and reciprocating crosshead flailing away. One wonders what a quick tip or bump would have done to one of the crew members....
I took these pictures in late April of 2005. Since my first experience inside the Ram, the museum staff has appeared to have cleaned up much of the inside and the engine appears in a very stable state of preservation. While much of the engine appears to be frozen with rust, it appears it could be freed up with little effort. Still, the Fenian Ram offers a wonderful opportunity to view one of the truly unique inventions in the history of internal combustion development. The Patterson museum is located in the Great Falls Historical district just off of Interstate 80.
If anyone is interested in this unique type of engine I’d be glad to try to answer any questions they may have. I can be reached at firstname.lastname@example.org or called at 410-392-0812. One of my back burner projects is to convert a 2 cylinder opposed piston compressor to a Brayton cycle oil engine
Figure 5- View of the crank throws. Note there are two to drive the crosshead from the outside.
Figure 6- Rear view of the Fenian on Display at the Patterson Museum